CVE-2019-3557 : Vulnerability Insights and Analysis

This CVE-2019-3557 article provides insights into a vulnerability affecting HHVM versions 3.30.1, 3.30.0, and 3.27.5, discovered on January 15, 2019.

Understanding CVE-2019-3557

What is CVE-2019-3557?

The vulnerability in HHVM versions 3.30.1, 3.30.0, and 3.27.5 allowed for out-of-bounds reads due to faulty implementations of stream functions for bz2 and php://output.

The Impact of CVE-2019-3557

The vulnerability could lead to out-of-bounds reads when certain stream functions were used, potentially causing security risks and data exposure.

Technical Details of CVE-2019-3557

Vulnerability Description

The readImpl functions of streams for bz2 and php://output in HHVM were implemented incorrectly, consistently returning -1, leading to out-of-bounds reads.

Affected Systems and Versions

HHVM 3.30.1
HHVM 3.30.0 (custom version)
HHVM 3.27.5

Exploitation Mechanism

The vulnerability could be exploited by utilizing stream functions like stream_get_line on the improperly formed streams, triggering out-of-bounds reads.

Mitigation and Prevention

Immediate Steps to Take

Update HHVM to the patched versions (3.30.2)
Monitor for any unusual activities on affected systems

Long-Term Security Practices

Regularly update software to the latest versions
Conduct security audits to identify and address vulnerabilities

Patching and Updates

Apply patches provided by Facebook for HHVM to address the vulnerability